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Separated laminar shear layer transition over a two-dimensional bump

  • Beihang University

Research output: Chapter in Book/Report/Conference proceedingConference contributionpeer-review

Abstract

The laminar boundary layer separation over a two-dimensional bump is experimentally investigated in a water channel with hydrogen-bubble visualization and particle image velocimetry (PIV) techniques, focusing on the characteristics of separated shear layer, the evolution of flow structure and the development of unstable disturbances. It is shown that the separation point, to a large extent, depends on the geometry of the bump, while the reattachment point is mainly affected by Reynolds number. A quite long and narrow separation bubble with its vortex centre located very close to the reattachment point is observed when the laminar boundary layer separates over the bump. The shear layer transition begins as soon as the laminar boundary layer flow is separated, with the flow field perturbation increasing rapidly to a maximum value and then decreasing slowly along the streamwise direction. The formation and shedding of two-dimensional spanwise vortex structures are observed along the shear layer due to Kelvin-Helmholtz instability. These spanwise vortices gradually lose their two-dimensionality and evolve into hairpin vortices downstream.

Original languageEnglish
Title of host publication29th Congress of the International Council of the Aeronautical Sciences, ICAS 2014
PublisherInternational Council of the Aeronautical Sciences
ISBN (Electronic)3932182804
StatePublished - 2014
Event29th Congress of the International Council of the Aeronautical Sciences, ICAS 2014 - St. Petersburg, Russian Federation
Duration: 7 Sep 201412 Sep 2014

Publication series

Name29th Congress of the International Council of the Aeronautical Sciences, ICAS 2014

Conference

Conference29th Congress of the International Council of the Aeronautical Sciences, ICAS 2014
Country/TerritoryRussian Federation
CitySt. Petersburg
Period7/09/1412/09/14

Keywords

  • Bump
  • Laminar flow separation
  • Separation bubble
  • Shear layer transition

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